Ionic conducting material containing an oligoether sulphate

The invention relates to an ion-conducting material containing an oligoether sulfate.The material comprises an ionic compound dissolved in a solvating polymer. The ionic compound is a mixture of a lithium bis(trifluoromethanesulfonyl)imide and of at least one lithium oligoether sulfate chosen from the lithium oligoether monosulfates corresponding to the formula R—[O—CH2—CH2)]n—O—SO3−Li+(I) in which R is a group CmH2m+1 with 1≦m≦4 and 2≦n≦17, and the lithium oligoether disulfates corresponding to the formula Li+O−SO2—O—CH2—[CH2—O—CH2]p—CH2—O—SO2—O−Li+(II) in which 3≦p≦45; the overall ratio Ot/Lit is less than or equal to 40, Ot representing the total number of O atoms provided by the solvating polymer and by the oligoether; the content of LiTFSI is such that the Ot/LiTFSI ratio is greater than or equal to 20.